阅读说明：本技术 铝硅涂层钢残余应力测量试样的制备方法及其测量方法 (Preparation method and measurement method of aluminum-silicon coated steel residual stress measurement sample ) 是由 薛峰 孙岩 孙晓冉 赵楠 葛晶晶 蔡啸 于 2020-12-17 设计创作，主要内容包括：本发明公开了一种铝硅涂层钢残余应力测量试样的制备方法及其测量方法,其方法步骤为：(1)从铝硅涂层热成型钢板中制取粗样；(2)所述粗样浸入10%～20%的稀盐酸溶液中,直到粗样的铝硅涂层边缘被溶解掉,中间部分开始脱落但未完全脱落时取出；(3)所述粗样浸入缓蚀盐酸溶液中,直至粗样的铝硅涂层完全脱落,取出；所述缓蚀盐酸溶液是在浓度≤10%的稀盐酸溶液中加入有缓蚀剂；(4)将涂层脱落后的粗样烘干,即可得到所述的试样。本制备方法先采用强酸化学清洗,可以有效去除大部分铝硅涂层；再在加有缓蚀剂的酸液中,去除剩余铝硅涂层；缓蚀剂的加入能够减小腐蚀速度,对钢板的原始残余应力不造成影响,从而有效地提升残余应力检测的准确性。(The invention discloses a preparation method and a measurement method of a residual stress measurement sample of aluminum-silicon coated steel, wherein the method comprises the following steps: (1) preparing a rough sample from the aluminum-silicon coating hot-formed steel plate; (2) the crude sample is immersed into 10 to 20 percent of dilute hydrochloric acid solution until the edge of the aluminum-silicon coating of the crude sample is dissolved, and the middle part of the crude sample begins to fall off but is not taken out completely; (3) immersing the crude sample into a corrosion inhibition hydrochloric acid solution until the aluminum-silicon coating of the crude sample completely falls off, and taking out; the corrosion inhibition hydrochloric acid solution is prepared by adding a corrosion inhibitor into a dilute hydrochloric acid solution with the concentration of less than or equal to 10 percent; (4) and drying the rough sample after the coating falls off to obtain the sample. The preparation method adopts strong acid chemical cleaning, so that most of the aluminum-silicon coating can be effectively removed; then removing the residual aluminum-silicon coating in the acid solution with the corrosion inhibitor; the corrosion inhibitor is added, so that the corrosion speed can be reduced, the original residual stress of the steel plate is not influenced, and the accuracy of residual stress detection is effectively improved.)

1. A preparation method of a residual stress measurement sample of aluminum-silicon coated steel is characterized by comprising the following steps: (1) preparing a rough sample from the aluminum-silicon coating hot-formed steel plate;

(2) the crude sample is immersed into 10 to 20 percent of dilute hydrochloric acid solution until the edge of the aluminum-silicon coating of the crude sample is dissolved, and the middle part of the crude sample begins to fall off but is not taken out completely;

(3) immersing the crude sample into a corrosion inhibition hydrochloric acid solution until the aluminum-silicon coating of the crude sample completely falls off, and taking out; the corrosion inhibition hydrochloric acid solution is prepared by adding a corrosion inhibitor into a dilute hydrochloric acid solution with the concentration of less than or equal to 10 percent;

(4) and drying the rough sample after the coating falls off to obtain the sample.

2. The method for preparing the aluminum-silicon coated steel residual stress measurement specimen according to claim 1, characterized in that: in the step (3), the volume of the corrosion inhibitor added is 1-3% of that of the dilute hydrochloric acid solution.

3. A method for measuring residual stress of the al-si coated steel according to claim 1 using the specimen according to claim 1 or 2, characterized in that: and testing the sample by adopting an X-ray diffraction method, and calculating to obtain the residual stress of the hot-formed steel plate.

Technical Field

The invention belongs to the field of metal material detection and analysis, and particularly relates to a preparation method and a measurement method of a residual stress measurement sample of aluminum-silicon coated steel.

Background

With the proposal of light weight and collision safety in the automobile industry, the hot forming process and technology of the hot forming high-strength steel are developed, and the steel is mainly applied to parts such as A columns, B columns, front and rear bumpers and the like of automobiles. Along with the improvement of the strength of parts, the fracture sensitivity is increased, and the cracking phenomenon appears after part of parts are subjected to heat treatment in the production process, so that the popularization and the application of the hot-formed high-strength steel market are limited.

The thermal forming process is characterized in that a constantly changing temperature field exists, the matrix structure and the mechanical property of the plate are changed under the influence of the temperature field, so that the stress field of the plate is changed, the change of the stress field of the plate is reacted on the temperature field, the temperature field and the stress field in the plate coexist and are mutually coupled, so that the residual stress of the part is unevenly distributed, and the part is easy to crack after heat treatment.

The method is used for carrying out residual stress test research on hot-formed steel, determining the quantitative relation between a heat treatment process schedule and a microstructure, the relation between a residual stress generating process and a distribution quantity value, and the relation between a part surface brittle failure mode and residual stress state distribution, and has guiding significance for the improvement of the heat treatment schedule.

When the X-ray diffraction method is adopted to test the residual stress of the hot formed steel, the coclination test needs to be carried out on the high-angle diffraction peak of iron, because part of the hot formed steel strip is provided with the aluminum-silicon coating, the X-ray can not directly act on the matrix during the test, and the actual residual stress of the hot formed steel can be accurately measured only after the aluminum-silicon coating is specially treated and the original residual stress of the hot formed steel is not influenced.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for preparing a residual stress measurement sample of aluminum-silicon coated steel without influencing the original residual stress

In order to solve the technical problems, the preparation method adopts the technical scheme that: (1) preparing a rough sample from the aluminum-silicon coating hot-formed steel plate;

(2) the crude sample is immersed into 10 to 20 percent of dilute hydrochloric acid solution until the edge of the aluminum-silicon coating of the crude sample is dissolved, and the middle part of the crude sample begins to fall off but is not taken out completely;

(3) immersing the crude sample into a corrosion inhibition hydrochloric acid solution until the aluminum-silicon coating of the crude sample completely falls off, and taking out; the corrosion inhibition hydrochloric acid solution is prepared by adding a corrosion inhibitor into a dilute hydrochloric acid solution with the concentration of less than or equal to 10 percent;

(4) and drying the rough sample after the coating falls off to obtain the sample.

In the step (3) of the preparation method, the volume of the corrosion inhibitor added is 1-3 vol% of the dilute hydrochloric acid solution. .

According to the measuring method, the sample is tested by adopting the sample and an X-ray diffraction method, and the residual stress of the hot-formed steel plate is calculated.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: according to the preparation method, strong acid is adopted for chemical cleaning, so that most of the aluminum-silicon coating can be effectively removed; then removing the residual aluminum-silicon coating in the acid solution with the corrosion inhibitor; the corrosion inhibitor can reduce the acid liquor corrosion speed, thereby having no influence on the original residual stress of the steel plate. The method has the characteristics of simple process, clean removal of the aluminum-silicon coating and no influence on the original residual stress of the steel plate, thereby effectively improving the accuracy of the residual stress detection of the aluminum-silicon coating hot-formed steel.

By adopting the measuring method, the residual stress test of the hot-formed steel plate containing the aluminum-silicon coating can be realized, and the aluminum-silicon coating can be effectively removed by adopting strong acid chemical cleaning; meanwhile, the corrosion inhibitor is added, so that the acid liquor corrosion speed is reduced, and the original residual stress of the steel plate is not influenced; the X-ray diffraction method is adopted, so that the measurement is accurate; has the characteristics of convenient detection and high accuracy.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a photograph of the surface of a primary etched sample obtained after primary etching according to the present invention;

FIG. 2 is a photograph of the surface of a sample obtained after corrosion inhibition according to the present invention;

FIG. 3 shows the X-ray diffraction peak positions of samples of example 1 of the present invention at different tilt angles;

FIG. 4 shows the X-ray diffraction peak positions of samples of example 2 of the present invention at different co-inclinations;

FIG. 5 shows the X-ray diffraction peak positions of samples of example 3 of the present invention at different tilt angles;

FIG. 6 is the residual stress level of the 22MnB5 sample after direct acid attack of comparative example 1;

fig. 7 is a graph of the residual stress level of the 22MnB5 sample after mechanical grinding of the aluminum silicon coating for comparative example 2.

Detailed Description

The preparation method and the measurement method of the residual stress measurement sample of the aluminum-silicon coated steel are as follows:

(1) preparing a sample: selecting an aluminum-silicon coating hot forming steel plate after quenching or hot forming deformation with proper size, and preparing a crude sample by adopting linear cutting; the coarse sample size is at least 30 x 30mm, and the surface is flat and has no scratch. The hot formed steel 22MnB5, 34MnB5 or other samples with aluminum silicon coatings.

(2) Initial etching: preparing a 10-20% dilute hydrochloric acid solution, immersing the rough sample into the dilute hydrochloric acid solution until the edge of the aluminum-silicon coating is dissolved, and taking out the rough sample when the middle part begins to fall off but does not fall off completely, thereby obtaining a primary etched sample, wherein a surface photograph of the primary etched sample is shown in figure 1.

(3) Corrosion inhibition: preparing dilute hydrochloric acid solution with mass concentration less than or equal to 10%, preferably 5-10%; adding corrosion inhibitor to prepare corrosion inhibition hydrochloric acid solution; the corrosion inhibitor is an acid pickling corrosion inhibitor, and the adding volume of the corrosion inhibitor is 1-3% of that of the dilute hydrochloric acid solution. Immersing the initial corrosion sample into the corrosion inhibition hydrochloric acid solution, taking out and drying after the residual coating substances completely fall off; a photograph of the surface of the sample obtained after corrosion inhibition is shown in FIG. 2.

(4) And wiping an oxide layer on the surface of the sample clean by using solid phosphoric acid, and clearly marking the orientation of the sample.

(5) Testing the sample by adopting an X-ray diffractometer and selecting a specific direction, selecting a homocline method, selecting a (211) crystal face as a rotation angle, and selecting different inclination angles to calculate sin phi²The value of (c).

(6) Calculating the residual stress of the hot-formed steel plate according to the result calculated by the homocline method; the change of the (211) interplanar spacing due to residual Stress can be calculated by the software of Pasnake X' Pert Stress. The residual stress value can be calculated according to the principle of material mechanics. The required Young modulus can be obtained by using a query value E =211.16GPa of a metal Young modulus meter and also by mechanical measurement.

Example 1: the specific process steps of the method for measuring the residual stress of the aluminum-silicon coated steel are as follows.

(1) Selecting hot-forming steel 22MnB5 with an aluminum-silicon coating after quenching at 930 ℃, wherein the thickness of the steel plate is 1.8 mm; and cutting the size of the steel plate to 30 x 40mm by adopting linear cutting, and marking the direction of the coarse sample to be measured clearly, wherein the surface of the coarse sample is flat and has no scratch.

(2) Preparing 20% dilute hydrochloric acid solution, immersing the crude sample into the prepared dilute hydrochloric acid solution, observing that the edge of the aluminum-silicon coating is dissolved and the middle part begins to fall off after 5 hours, and taking out to perform the next step.

(3) Preparing a dilute hydrochloric acid solution with the concentration of 10%, and adding 1% of corrosion inhibitor; and (3) immersing the primary etched sample into a corrosion inhibition hydrochloric acid solution, taking out after the residual coating substances completely fall off after 8 hours, and drying. The pickling corrosion inhibitor produced by Shijiazhuang Bora science and technology limited company is adopted.

(4) And wiping an oxide layer on the surface of the sample by using solid phosphoric acid, and marking the rolling direction.

(5) Testing the hot-formed steel plate with the coating taken out by adopting an X-ray diffractometer and selecting a specific direction, selecting a homocline method, selecting a (211) crystal face as a rotation angle, and selecting 6 different inclination angles in total to calculate sin phi²The value of (c).

(6) According to a homocline method, calculating the residual Stress of the hot-formed steel plate by X' Pert Stress software of the Pasnake software, wherein the Young modulus of the steel plate is selected to be E =211.16 GPa; the matrix residual stress of the 22MnB5 hot-formed steel is-195.2 +/-54.4 MPa, and the stress is compressive stress, and is shown in a figure 3 in particular.

Example 2: the specific process steps of the method for measuring the residual stress of the aluminum-silicon coated steel are as follows.

(1) Selecting hot forming steel 22MnB5 with an aluminum-silicon coating after hot forming deformation, wherein the thickness of the steel plate is 2.5 mm; and cutting the size of the steel plate to 40 × 40mm by adopting linear cutting, marking the deformation direction of the rough sample clearly, selecting the deformation direction as the measurement direction, and flattening the surface of the rough sample without scratches.

(2) Preparing a 10% dilute hydrochloric acid solution, immersing the crude sample into the prepared dilute hydrochloric acid solution, observing that the edge of the aluminum-silicon coating is dissolved and the middle part begins to fall off after 20 hours, and taking out to perform the next step.

(3) Preparing a dilute hydrochloric acid solution with the concentration of 8%, and adding 3% of a corrosion inhibitor; and (3) immersing the primary etched sample into a corrosion inhibition hydrochloric acid solution, taking out after the residual coating substances completely fall off after 6 hours, and drying. The pickling corrosion inhibitor produced by Shijiazhuang Bora science and technology limited company is adopted.

(4) And wiping an oxide layer on the surface of the sample by using solid phosphoric acid, and marking the rolling direction.

(5) An X-ray diffractometer is adopted, a specific direction is selected for testing a sample, a homocline method is selected, a (211) crystal face is selected as a rotation angle, and 6 different inclination angles are selected in total for calculating sin phi²The value of (c). (6) According to a homocline method, calculating the residual Stress of the hot-formed steel plate by X' Pert Stress software of the Pasnake software, wherein the Young modulus of the steel plate is selected to be E =211.16 GPa; the matrix residual stress of the 22MnB5 hot-formed steel is-549.4 +/-150.4 MPa, and the stress is compressive stress, and is shown in figure 4 in particular.

Example 3: the specific process steps of the method for measuring the residual stress of the aluminum-silicon coated steel are as follows.

(1) Selecting hot forming steel 34MnB5 with an aluminum-silicon coating after hot forming deformation, wherein the thickness of the steel plate is 2.2 mm; and cutting the size of the steel plate to 30 x 30mm by adopting linear cutting, marking the deformation direction of the rough sample clearly, and selecting the measurement direction perpendicular to the deformation direction, wherein the surface of the rough sample is flat and has no scratch.

(2) Preparing 15% dilute hydrochloric acid solution, immersing the crude sample into the prepared dilute hydrochloric acid solution, observing that the edge of the aluminum-silicon coating is dissolved and the middle part begins to fall off after 10 hours, and taking out to perform the next step.

(3) Preparing a dilute hydrochloric acid solution with the concentration of 5%, and adding 2% of a corrosion inhibitor; and (3) immersing the primary etched sample into a corrosion inhibition hydrochloric acid solution, taking out after the residual coating substances completely fall off after 8 hours, and drying. The pickling corrosion inhibitor produced by Shijiazhuang Bora science and technology limited company is adopted.

(4) And wiping an oxide layer on the surface of the sample by using solid phosphoric acid, and marking the rolling direction.

(5) An X-ray diffractometer is adopted, a specific direction is selected for testing a sample, a homocline method is selected, a (211) crystal face is selected as a rotation angle, and 6 different inclination angles are selected in total to calculate sin phi²The value of (c).

(6) According to a homocline method, calculating the residual Stress of the hot-formed steel plate by X' Pert Stress software of the Pasnake software, wherein the Young modulus of the steel plate is selected to be E =211.16 GPa; the matrix residual stress of the 22MnB5 hot-formed steel is-447.0 +/-104.3 MPa, and the stress is compressive stress, and is shown in a figure 5.

Comparative example 1: the following process steps are adopted.

(1) Selecting hot forming steel 22MnB5 with an aluminum-silicon coating after hot forming deformation, wherein the thickness of the steel plate is 2.2 mm; and cutting the size of the steel plate to 30 x 30mm by adopting linear cutting, marking the deformation direction of the rough sample clearly, and selecting the measurement direction perpendicular to the deformation direction, wherein the surface of the rough sample is flat and has no scratch.

(2) Preparing a dilute hydrochloric acid solution with the mass concentration of 15%, and taking out the sample after standing for 48 hours.

(3) And cleaning the surface.

(4) Measuring the surface residual stress of the sample, selecting a homocline method, selecting a (211) crystal face as a rotation angle, and selecting 6 different inclination angles to calculate sin phi²The value of (c). (6) According to the cocurrent method, the Parnacidae software X' Pert StreCalculating the residual stress of the hot-formed steel plate by ss software, wherein the Young modulus of the steel plate is selected to be E =211.16 GPa; the residual stress of the matrix of the 22MnB5 hot-formed steel is-82.8 +/-8.8 MPa, and the stress is compressive stress, and is shown in figure 6 in particular.

Comparative example 2: the following process steps are adopted.

(1) Selecting hot forming steel 22MnB5 with an aluminum-silicon coating after hot forming deformation, wherein the thickness of the steel plate is 2.2 mm; and cutting the size of the steel plate to 30 x 30mm by adopting linear cutting, marking the deformation direction of the rough sample clearly, and selecting the measurement direction perpendicular to the deformation direction, wherein the surface of the rough sample is flat and has no scratch.

(2) And (3) polishing the surface of the sample by using a grinding disc, wherein 180# abrasive paper is selected as the abrasive paper, and polishing until the aluminum-silicon coating completely disappears.

(3) Measuring the surface residual stress of the sample, selecting a homocline method, selecting a (211) crystal face as a rotation angle, and selecting 6 different inclination angles to calculate sin phi²The value of (c). (6) According to a homocline method, calculating the residual Stress of the hot-formed steel plate by X' Pert Stress software of the Pasnake software, wherein the Young modulus of the steel plate is selected to be E =211.16 GPa; the 22MnB5 hot-formed steel has a matrix residual stress of 175.6 + -13.9 MPa, which is a tensile stress, as shown in FIG. 7.

As can be seen from examples 1 to 3 and comparative examples 1 to 2, the method does not affect the residual stress of the hot-formed steel sheet while the aluminum-silicon coating is etched off; according to the use process of hot formed steel, theoretically, the hot formed steel after quenching has a large compressive stress due to the presence of the transformation stress, as shown in examples 1, 2 and 3. In order to prove that the measurement result of the method is accurate, two groups of comparison tests are specially carried out, as shown in comparative examples 1-2, the test sample is excessively acid-etched and the polished test sample respectively, the excessive acid-etched test can reduce the compressive stress of the test sample, the polished test sample can cause larger tensile stress, and the method is not in accordance with the theoretical situation. According to common knowledge in the technical field, the quenching stress should be a large compressive stress, which is consistent with the result measured by the method.